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Magnepan Magneplanar MG1.6/QR loudspeaker Measurements

Sidebar 3: Measurements

The MG1.6/QR plays significantly quieter than the Thiel CS2.3 for the same voltage input. I estimated its B-weighted sensitivity at a low 83.7dB(B)/2.83V/m, though this will be moderated somewhat by its line-source behavior in-room. Its impedance (fig.1) is basically that of a 4.5 ohm resistor, modified by the crossover, which results in the peak at 600Hz. Any good 4-ohm-rated amplifier should be able to drive the Maggie without difficulty. There are no cabinet resonances—the MG1.6/QR doesn't have a cabinet.

Fig.1 Magnepan MG1.6/QR, electrical…

Cary Audio Design CAD-805 monoblock power amplifier

Lee de Forest filed for a US patent on his "Audion"—the first triode—on October 25, 1906, but never could explain why it worked (footnote 1). It was up to Armstrong and Langmuir, in their pioneering work, to place the hard-vacuum triode on firm scientific ground. When the US entered World War I in April 1917, the Army had to rely on French tubes. Six months later, Western Electric was mass-producing the VT-1 receiving tube and the VT-2 transmitting tube. However, it was only in the decade following World War I, as designers became conversant with the triode amplifier, that many of the…

Cary Audio Design CAD-805 monoblock power amplifier Page 2

Cary's 805 (at last)
With its ornate knobs and gold-on-black finish, the beautifully crafted Cary Audio Design 805 looks like a '30s period piece. A delightful feature is the "tuning eye" on the front panel. The eye, which monitors the AC output voltage, closes completely at the 50W output level. The open chassis is dominated by the large—almost 8" from head to toe—211 output tube. This true three-element tube has been heavily used over the years in RF amplifiers. The filament, a directly heated thoriated-tungsten type, requires a current of 3.25 amps at 10VAC. The 211's plate…

Cary Audio Design CAD-805 monoblock power amplifier Page 3

The impedance magnitude should be fairly flat for efficient power delivery. The nominal impedance should be 8 ohms or higher, and ideally there should be no dips below 4 ohms—at least below 500Hz. Any tube amp is limited in its current delivery, and the lower the load impedance, the greater the current demand. As a simple example, compare two loudspeakers: one with an 8 ohm impedance vs one with a 4 ohm impedance. Assuming purely resistive loads, the current demand of the 4 ohm load is twice that of the 8 ohm load. I'm appalled at the recent trend toward vanishing-impedance loudspeakers. An…

Cary Audio Design CAD-805 monoblock power amplifier Page 4

Again, wonderful things were happening to human voice with the Cary. Rich and almost palpable, the individual voices of a chorus floated in space with remarkable resolution. The sensation of being able to pinpoint isolated singers in an ensemble was very believable. There was something about the 805 that made human voices sing more soulfully. The ability to convey human emotions transcended the realm of mere reproduction.

Even off the 4-ohm taps, the bass lacked impact and a convincing foundation. Taj Mahal's "John Henry's Fiddle" (string bass) on "Texas Woman Blues" (from Recycling the…

Cary Audio Design CAD-805 monoblock power amplifier Page 5

The Mozart and the 805 formed a synergistic duo. Objectively, the Mozart's upper registers are lively, with a notable metallic flavor characteristic of all the Scandinavian aluminum-dome tweeters I've heard. With the Classé M-700 solid-state monoblock, the metallic aroma had no place to hide. The 805, on the other hand, civilized the Vifa tweeter to the point of respectability. Again, I found 5dB of feedback to be an ideal balance between lushness and intimacy.

The Mozart simply brought out the 805's best, resulting in a fully 3-D illusion of space. Not only were instrumental outlines…

Cary Audio Design CAD-805 monoblock power amplifier Dick Olsher 2/94

Dick Olsher wrote again about the CAD-805 in February 1994 (Vol.17 No.2):

Something that really sets Toob Man's heart aglow is the igniting of the 805's mighty 211 power triode tube. When I dim the room lights and throw the filament power switch, the thoriated tungsten filament—at 3 amps and 10V—illuminates like a 30W light bulb. Both the 211's "furnace" and its grid structure are clearly visible through the top of the glass envelope—man, what a sight.

The 211 first came on the scene in 1919 as a radio transmitting tube, courtesy of the folks at the great Western Electric Company…

Cary Audio Design CAD-805 monoblock power amplifier Martin Colloms 5/94

Martin Colloms wrote about the CAD-805 in May 1994 (Vol.17 No.5):

My excitement grew as I stripped the wrapper from the first new, larger Stereophile (January 1994). First reactions were favorable: it was brighter, better presented, easier to read, and had more impact. I welcomed the change, even if it does mean my Stereophiles no longer fit on the old, narrow shelf on my bookcase where they once shared space with my digest-sized editions of Hi-Fi Choice.

There was so much to read that it took a while to come to grips with the magazine. Only a day or so after it arrived did I…

Cary Audio Design CAD-805 monoblock power amplifier Sam Tellig 3/98

Sam Tellig wrote about the CAD-805 in March 1998 (Vol.21 No.3):

It takes courage to buy an amp like the Cary CAD-805C—so retro in its technology and its look.

"You bought those," my friend Pavel said, referring to the CAD-805C monoblocks in my listening room. "Wait till I tell my friends back in Russia. We couldn't wait to get rid of tubes."

Ha-ha-ha.

Or kcha-kcha-kcha, as they say in Russia, there being no h in Russian. It is thus that Handel, Haydn, and Horowitz are transformed into Gandel, Gaydn, and Gorowitz. And Dennis Had, President of Cary Audio Design,…

Cary Audio Design CAD-805 monoblock power amplifier Sam Tellig 3/98 part 2

Ah...the palpable presence of the musicians. The exquisite low-level detail. The perfect timing of the attack and decay of each note. Above all, the truth of timbre and the sheer beauty of the music.

Don't you just hate it when that happens?

If you don't hate it, you may love single-ended triodes.

Digression
One of the great joys of discovering single-ended triodes is that you may start enjoying certain kinds of music that you find largely unlistenable with non-SET triode amps. Take chamber music, for instance.

"Yes, take it," you say. But wait.

If…